Both "contact" and "contactless" devices are known per se. Generally, such devices are in the form of smart cards provided either with electrical contacts for effecting direct electrical contact with a card reader; or else they are provided with a coil antenna for effecting contactless bi-directional communication with a remote card reader. U.S. Pat. No. 5,206,495 for a Chip Card in the name of H.D. Kreft discloses a chip card allowing both contact and contactless communication in a single smart card.
Contactless smart cards are particularly suited for applications, such as mass transport systems, wherein data communication must be effected very is quickly without imposing the overhead incurred in manually introducing the smart card into the slot of a card reader.
U.S. Pat. No. 5,206,495 has as a principal object thereof the provision of a contact/contactless chip card having a microprocessor selectively coupled either to a contact field or to a coil. A further declared feature is that the microprocessor operates according to contact mode protocol (ISO Standard 7816) regardless of the mode of data transfer, such that the microprocessor 14 perceives no difference between contact and contact-free use of the chip card.
Such chip cards employ an on-board microcomputer including memory and processing capability for effecting the desired bi-directional data transmission and data storage. In the case where "contact" data transmission is required, there is provided a so-called "contact field" having a plurality of contacts, each of which is connected to the microcomputer by means of a respective electrical connection. Data transmission with an external reader is then effected by inserting the card into a suitable reader having spring-loaded contacts which bear on respective contacts in the contact field of the chip card.
Alternatively, when contactless data transmission is required, a coil antenna in the chip card is adapted to receive data from and transmit data to a reading device having a similar antenna.
FIG. 1 shows the interconnection of functional elements of the chip card subject of U.S. Pat. No. 5,206,495 and employs the same reference numerals as are used in the description of the U.S. Patent. Thus, a switching element device 2.1 connects either a contact field 3 or a pair of coils 4 and 5 to a semiconductor device 2.
Preferably, the switching element device 2.1 is a multiplexer which serves to select either the coils 4 and 5 or the contact field 3 and feed the data received thereby to the semiconductor device 2. Because the data provided by the switching element device 2.1 to the semiconductor device 2 is the same, whether it originates from or is transmitted via the contact field 3 or the coils 4 and 5, the semiconductor device 2 perceives no difference between contact and contactless use of the chip card 1.
Thus, the interconnection provided by U.S. Pat. No. 5,206,495 allows for a microprocessor conforming to ISO Standard 7816 for "contact" bi-directional data transmission also to be used for "contactless" type data transmission without in any way modifying the microprocessor. On the other hand, such an approach exacts a price in the efficiency of data transfer owing to the inherent differences between contactless data protocols and the ISO 7816 contact protocol, which thus requires that the card include a data conversion facility if the microprocessor is to perceive the same protocol in both contact and contactless modes. The use of two coils is also considered a retrograde step reminiscent of the early U.S. Pat. No. 3,299,424 (Vinding) wherein multiple coils were employed: a trend which has long been abandoned in favor of the use of a single coil only.
Yet a further consideration associated with the increasing use of smart cards is the need to customize each smart card for the particular application for which it is destined. Obviously, the provision of both contact and contactless modes of data transfer increases the card's versatility since the actual mode of data transfer may then be selected according to user requirements. However, in practice, there are many other features associated with smart cards which also must be optimized for each specific application, be it contactless access control or mass transportation or contact mode bank applications and so on.